So I was on my way to work yesterday and was using the four-wheel drive, and on the freeway I suddenly heard a loud humming noise, almost droning. I put the truck in neutral, shifted it into 2H and disengaged the four-wheel drive. I got off the freeway and soon before I come to a stop, it felt like I had to hold the wheel to the right to stop it from pulling to the left, so I let go of the wheel, and it pulled really hard to the left. So I pulled into a gas station and looked underneath the truck but didn't notice anything unusual. No broken axels or cv joints. A friend from work told me it could be the u-joints because he has a similar problem with his F-150, but I wanted a few second opinions. BTW, it's a '94 Nissan Pathfinder w/ floor shift 4x4 and automatic locking hubs. Thanks in advance guys!